The invention relates to the production of mineral fiber material, and more particularly, to materials such as glass fibers. Specifically, the invention relates to making loose fibrous material of a type suitable for the manufacture of fiber glass products including loose-fill, blown-in type insulation.
Loose-fill insulations are either produced asxe2x80x94or broken down intoxe2x80x94shreds, granules, or nodules. These small particles form fluffy materials that conform to the spaces in which they are installed. Loose-fills are most commonly sold in bags and are blown into building cavities using special equipment.
Loose-fill insulations are well suited for places where it is difficult to install other types of insulation, for example, irregularly shaped areas, around obstructions (such as plumbing stacks), and in hard-to-reach places. They can be installed in either enclosed cavities such as walls or unenclosed spaces such as attics. Blown-in loose-fills are particularly useful for retrofit situations because, except for the holes that are sometimes drilled for installations, they are one of the few materials that can be installed without greatly disturbing existing finishes.
One common type of loose-fill, fiber glass loose-fill insulation is spun from molten glass into fibers. The glass is typically melted in high-temperature gas or electric furnaces and often includes about 20% to 30% of recycled glass content.
There are several performance characteristics to consider when selecting a loose-fill insulation material. Among the most important to consider are insulating capacity, weight, convective heat loss, settling and loss of insulating capacity. A material""s resistance to heat flow is expressed as its R-value. The higher the R-value, the better the material insulates, and the lesser the thickness required to achieve a desired result.
Loose-fill insulations are produced by a variety of methods known in the art. For example, a common method of production involves supplying streams of molten glass to conventional rotary fiberizers to form veils of glass fibers. At this point, an additive, usually an anti-static organic agent, is applied to the glass fibers. These veils of glass fibers are typically collected onto conveyors, then pass though equipment, such as a flail which cuts and shreds them into fiber nodules. From that point, the nodules are pneumatically conveyed to other conditioning equipment where special additives such as dust reduction oil are applied, then through a nodulator for further conditioning and finally to packaging equipment.
The processing steps of cutting and shredding loose-fill fiber glass insulation are often very rough processing and not efficient. Higher performance cutting and shredding of loose-fill insulation is cost prohibitive, requiring the manufacturer to purchase and maintain separate and expensive machinery to produce the desired form of the insulation. Another problem with conventional processing techniques is that they tend to produce a dispersed glass fiber nodule size. That is, the nodule size generally is not uniform. A more uniform nodule size would permit a better additive distribution, which would in turn optimize the products performance as an insulation.
Improved methods of and apparatus for forming loose-fill fiber glass insulation materials with less dispersed glass fiber nodule size distribution are therefore desirable.
The present invention provides for a system for conditioning glass fiber nodules, the system including a conditioning duct having an elongated cylindrical tube with a plurality of blades disposed in a helical configuration around the cylindrical tube. The blades extend radially inward from an inside surface of the cylindrical tube and serve to break apart the veils of glass fibers to provide a more uniform nodule size distribution than otherwise obtained using conventional techniques. The conditioning duct is in preference installed between the flail and the nodulator in order to offer an efficient fiber cutting and shredding, although it could be installed in other areas of pneumatic transport duct.
An air inlet may also be incorporated into the conditioning duct, whereby pressurized air enters the inlet and provides a tangential airflow through the duct. The air flowing into the duct via the inlet induces a rotation in the glass fiber nodules disposed in the duct and serves to push the nodules through the blades.
Another aspect of the system lies in a method for processing loose-fill insulation is provided and includes the step of: passing loose-fill insulation material through an elongated duct having a plurality of internally disposed blades in a helical configuration. Tangential airflow may also be provided to the duct to impart a rotational effect on the insulation materials for improved processing through the duct.